The long term goal of this research program is to understand the role of micronutrient deficiency on the health and well-being of women and children in underdeveloped areas of the world. Previous studies conducted by the investigators in Nepal have demonstrated large reduction on preschool child and maternal mortality with vitamin A supplementation. The aims of this project are to evaluate the impact of zinc supplementation on mortality of children three to 36 months of age who are already receiving routine vitamin A supplementation. Previous work suggests that zinc deficiency plays an important role in increased risk of morbidity and, perhaps, mortality. The study is designed as a randomized, placebo controlled, community-based clinical trial to be conducted in a well defined study area of southern Nepal. This area was chosen because of a strong community-based research infrastructure and the ability to generalize findings to other populations on the Indian subcontinent. Approximately 36,000 children will be recruited over a two year period and randomized to receive either daily supplementation of zinc sulfate or placebo. Weekly visits by the field team will record vital events in participating households and morbidity experienced by the child over the past week. In a subsample, they will assess the impact of supplementation on zinc status and growth over a two year period. The analysis will focus on comparison of rates of mortality and morbidity between treatment groups with additional analyses of subgroups to look for interaction by age, gender or baseline nutritional status.